It is known that digital signatures can be used to uniquely identify files. It is known that two files can be compared to identify their differences. It is known that content management systems endeavor to reduce disk consumption by reducing duplication within an enterprise. It is known that offsite backup of essential files are among best practices for data security. It is known that public/private key pairs are used for asymmetric encryption. When one key of a key pair is used to encrypt a message, the other key from that pair is required to decrypt the message. Conventional backup systems provide services for individuals or corporate customers. However bandwidth considerations are more limiting than raw disk capacity. It can be appreciated that a more efficient backup solution would lower duplicative transfers.